Optical coherence tomography performs cross-sectional imaging, three-dimensional imaging, or data acquisition in materials or biological tissue by measuring the magnitude and time delay of backscattered or backreflected light from inside the sample. OCT performs imaging or measurement by directing a light beam at the sample, measuring the backscattering or backreflected signal from the sample as a function of the optical delay (known as an axial scan or A-scan), and scanning the OCT beam incident on the tissue or material to generate a two or three dimensional dataset which represents cross-sectional or volumetric information about the internal structure of the sample. In the case where the dataset includes a set of axial scans at sequential transverse positions, it is usually displayed as false color or grey scale images which represent cross-sections through the sample.
Directing and aiming of OCT beam scanning by a human operator is subject to speed and accuracy limitations and may not be feasible in many OCT applications. Prior systems for improving the registration of OCT images or data to landmarks or features on the sample have used an active tracking system, which required a separate optical tracking beam to actively control the position of the OCT beam with respect to the sample. However, the requirement of a second tracking beam in active tracking systems adds significantly to the complexity of the OCT apparatus and is also impractical for many OCT applications, such as for endoscopy.
Accordingly, a need therefore exists for techniques and devices that improve the efficiency by which OCT data is collected. Methods that enable accurate data collection from specific regions of a sample within short time periods are also desirable.